Glycerinated paper



July 3, 1934. G, A, RICHTER 1,964,793

GLYCERINATED PAPER Filed Jan. 30, 1932 Patented July 3, 1934 PATENT OFFICE GLYCERINATED PAPER George A. Richter, Berlin, N. H., assigner to Brown Company, Berlin, N. H., a corporation o! Maine Application January 30, 1932, Serial No. 589,867

1 claim. (o1. 154-46) This invention relates to glycerinated papers having a set of characteristics rendering such papers highly desirable for writing, printing, and other purposes.

In accordance with the present invention, I

prepare glycerinated papers whose glycerine component is non-uniformly distributed therethrough. This non-uniform distribution extends inwardly through its body or thickness from its exterior surfaces. More especially, the paper of the present invention is far richer in glycerine in its interior than at its surface layers. In fact, I prefer to have the surface layers substantially devoid of glycerine. Such a paper can conveniently be made on a multi-cylinder papermaking machine as a sheet composed of at least three plies, the internal ply being glycerinated and the external plies being substantially devoid of glycerine or of gradually decreasing glycerine concentration toward the exterior surfaces. The external plies may, however, advantageously be sized and/or filled with the usual papermaking ingredients so as to have the proper receptivity toward writing and printing inks.

A paper embodying the present invention has a valuable combination of qualities. The glycerine component enhances the pliancy and folding endurance of the paper. Nevertheless, the glycerine isnot present at the surfaces, where it would interfere with ink-receiving properties of the paper and impart an objectionable damp and soft feel, as well as a at appearance thereto.

` The fact is, that the absence of glycerine at the surface layers permits the paper to exhibit the desired rattle and hardness, particularly when the surface layers are sized with rosin, glue, casein, starch, silicate, viscose, or the like, even though the interior of the paper is highly glycerinated with a view toward greatly appreciating the pliancy and folding endurance of the paper. Along with the glycerine present in the interior or inner plydof the paper, lmay be glue or other sizing agent. So, too, fillers, dyes, or other papermaking ingredients maybe present in the interior or inner ply of the paper, as well as in the surface layers or plies. l

With the foregoing and other features and objects in view, my invention will now be described in further detail in conjunction with the accompanying drawing, wherein tionally a type of papermaking machine which i lends itself to application in making the paper of. the present invention.

Figure 2 represents an enlarged section through a paper embodying the present invention.

The machine shown in Figure 1 is a multicylinder papermaking machine comprising three vats and cylinders, and hence serviceable in making a three-ply paper. Of course, a machine having a larger number of vats and cylinder units might be employed, but for the purpose of illustration I have chosen a machine with the fewest units. Each of the units comprises a vat 1, into which the paper making stock is delivered at the proper rate as an aqueous suspension of the desired consistency. The stock is deposited as a layer or ply on a rotary cylinder or mould 2,.which rotates partially submerged in the aqueous susmay be ensured by causing the felt-4 to pass over a suction box 6 during or after the application of glycerine to substantially the"entire upper or exposed surface of the ply. A felt 7 picks up the plv from the third cylinder, Each of the pickup felts can bedirected by the" appropriately located guide rolls shown, to a suction roll 8 about which passes a transfer felt 9 serving as the carrier for the superposed plies. As shown, the ply on the pick-up felt '7 is first sucked onto the felt 9, whereafter the plies on the pick-up felts 4 and 3 are successively laid against the iirst ply transferred lto the felt 7. The. wet condition of the plies, as well as the suction applied duringv 'be conveyed by the felt 9 to a suitable drier, for

instance over a bank of theusual heated drier drums (not shown), which delivers the sheet in a completely dewatered condition.

While there may be some migration of glycerine from the internal glycerinated ply to the external plies, especially while the plies are still wet with water, nevertheless the water present in the external plies will serve to dilute such glycerine as diffuses thereinto in a manner such that the concentration oi' glycerine will diminish progressively toward the exterior surfaces of the outer plies. The 4resulting sheet will therefore be one which, as illustrated in Figure 2, has an internal ply a rich in glycerine, and external plies b poor in or lacking glycerine. Once the water content of the sheet is removed, there is little tendency for the viscous glycerine to enter from the inner ply into the outer plies, especially when the outer plies alsA are sized. The sizing materials may be present in the stock suspension delivered into the cylinder Vats for the outside plies. 'I'he stock for the outer plies, or, for that matter, all`of` the plies, may be prepared in beater engines in which the stock is well hydrated or'beaten so as to lead to plies. of a more or less dense or compact texture and high Mullen strength. When the outer plies are made from such stock, they do not favor the inux of glycerine from the inner, glycerinated ply. Rather than glycerinating'a preformed inner ply, it is possible to glycerinate the stock used for this ply. In such latter case,' the glycerine may be added either to the beater or to the cylinder vat in which the stock for the inner ply is handled.

The principles of the present invention extend to composite papers or boards made by pasting orvsticking together three or more prefabricated paper plies through the use of suitable pastes or adhesives as the bonding agents. In accordance with the present invention, the inner ply or plies of such papers or boards may be thoroughly glycerinated, Whereas the outer plies can be sized and contain such iillers as china clay but be practically lacking in glycerine. Such papers or boards may be calendered to present a smooth and glossy surface, which takes -writing and printing inks nicely and which is eminently serviceable for such uses as business or personal cards. The glycerinated interior of such papers or boards improves their exing quality and folding endurance, without interfering with the surface characteristics sought therein.

The papers of the present invention possess a higher tear resistance 'and bursting or Mullen strength than when paper is uniformly glycerinated. Moreover, a paper which is well glyceri- 'nated throughout tends to undergo deterioration, .for upon ageing not only does thepaper lose markedly in tear resistance, but the glycerine on the surface tends to oxidize, especially in the presence of air and sunlight, and to acquire a sticky condition. When the glycerine is present in signiflcant concentration only in the interior of the paper, the surface of the paper remains unimpaired, and there is much less tendency for the paper to deteriorate on ageing. It is, of course, possible to produce papers embod-ying the present invention and yet possessing widely different degrees of exibility and folding endurance, depending upon such factors as the precise amount of glycerine used in the inner ply and the quality of the stock and the kind and amounts of sizing, filling agent, or other papermaking ingredients used in the outer plies.

What I claim is:

A multi-ply paper composed of lat least three plies, the internal ply being glycerinatecl and the external piles being substantially devoid of glycerine.

GEORGE A. RICHTER. 

